No one is believed to have been injured. The plume of smoke has been seen by people in Steventon, Didcot and Goring.

A fire service spokesman said: "Ten fire engines supported by a water carrier, incident support unit, rescue tender and aerial appliance are currently on the site. The fire is in the vicinity of an area dedicated to hazardous chemical waste.

"The fire and rescue service is advising anyone living in the immediate vicinity to stay indoors and keep their windows closed as a precuation."

The police have advised people living as far away as Sonning Common and Nettlebed to keep their windows and doors shut.

Roads around the site have also been closed.

Police spokesman James Williams said: "The fire service is at the scene and tackling the blaze, with Thames Valley Police helping to enforce a 200 meter cordon around the site.

"Members of the public are advised to avoid the area.

A tweet from the police helicopter above the Grundon plant

"One private building outside the site has been evacuated."

A tweet from the police helicopter above the Grundon plant

South Central Ambulance Service spokesman Michelle Archer said it was called at 8.04pm and sent an ambulance, three officers and a hazardous area response team.

She said there were no reports of any injuries and paramedics will remain at the scene.

Pictures courtesy of reader @Luuunatik

According to a planning application submitted by the company in 2012, Grundon's operations at the Ewelme depot date back to the 19th Century.

The centre was processing about 7,500 tonnes of hazardous waste a year.